High speed veneering process



' Dec. 21, 1965 ELMENDORF 3,224,919

HIGH SPEED VENEERING PROCESS Filed Dec. 21, 1962 2 Sheets-Sheet 1 M V 3#7 K 30 J L 1 y 3 INVENTOR.

Dec. 21, 1965 A. ELMENDORF 3,224,919

HIGH SPEED VENEERING PROCESS Filed Dec. 21, 1962 2 Sheets-Sheet 2 7 a 3IN VEN TOR. j Jim/M [Zia/M90;

United States Patent 3,224,919 HIGH SPEED VENEERING PROCESS ArminElmendorf, 860 Charleston Road, Palo Alto, Calif. Filed Dec. 21, 1962,Ser. No. 246,593 3 Claims. (Cl. 156299) This invention relates to a highspeed veneering process and is a continuation in part of my co-pendingapplication Serial No. 84,086, filed January 23, 1961, now abandoned.

A primary purpose of the invention is a high speed veneering process inwhich strips of veneer are moved into edge contact with each other andline bonded to a moving panel, prior to the final permanent bondingstep.

Another purpose is a process for splicing thin dry veneer on a movingpanel.

Another purpose is an automated method, suitable for high speedoperation, for veneering panels.

Another purpose is a method of the type described requiring a minimum ofmanual labor.

Other purposes will appear in the ensuing specification, drawings andclaims.

The invention is illustrated diagrammatically in the following drawingswherein:

FIGURE 1 is a diagrammatic illustration of the various steps in my highspeed veneering process,

FIGURE 2 is a side view, with parts in section, of an apparatus forsplicing veneer,

FIG. 3 is a partial vertical elevation through the apparatus illustratedin FIGURE 2, and

FIGURE 4 is a partial vertical section through the press used inpermanently bonding the veneer to the panel.

In FIGURE 1, a stack of panels is indicated at 10. Any type ofligno-cellulosic panel such as particle board, plywood, insulationboard, hardboard, or the like, may be veneered in this process. Onesurface of each of these panels has been coated with an adhesive and theadhesive has been dried. This step is completed prior to stacking thepanels and may be performed in any conventional manner. The type ofadhesive may vary, although some types of melamine adhesives as well assome protein adhesives are satisfactory. It is preferred to apply the adhesive as a solution after which it is force dried.

A workman may take one of the panels from the stack and lay this panelacross a pair of spaced belts 12 or some other suitable conveyorarrangement. Any conventional drive may be used. The belts 12 arestationary when a panel, indicated at 14, is placed on them. A thinsheet of veneer, in a dry state, is placed along one edge of the panel14, as indicated at 16. The workman may flatten the sheet 16, as thinveneers are frequently badly buckled, and may then temporarily bond thisfirst sheet to the adhesive coated surface of the panel to provide a setedge against which a succeeding veneer sheet may be shoved. This bondingmay be accomplished in any manner, but preferably by applying heat atspaced points or along spaced lines to activate the adhesive. This maybe done while the panel is stationary or moving. Next, additional veneersheets, indicated at 18, with the number of additional veneer sheetsdepending upon the size of the panel and the size of the veneer, areplaced on the adhesive coated surface in a generally parallelarrangement with the veneer sheet 16. Adjacent edges of the veneersheets 18 are not in contact. The edge of each sheet is spaced a smalldistance from its adjacent edge. The forming line is still at rest asthe above operation is taking place.

After the sheets 18 have been placed in position on the panel 14, thebelts 12 are started in motion and the panel is removed through asplicing zone indicated generally at 20. At the splicing zone anadjoining veneer sheet 3,224,919 Patented Dec. 21, 1965 18 is pushedagainst the edge of temporarily bonded sheet 16 and then said sheet 18is temporarily bonded to the panel along parallel lines. This operationtakes place as the panel is moving. The belts will stop when the panelreaches the station indicated at 22. A second panel is now removed fromthe stack 10 and veneer sheets are placed on it in the manner described.The belts 12 are again started and the panels move, in the direction ofarrow 23, with the stationary panel at station 22 being moved into a hotplate press indicated at 241. The panel will remain in the press asufficient time to permanently bond the veneer sheets to the surfaces ofthe panels, which were previously line bonded at the splicing zone 20,to the panel.

The pressing cycle may take about 20 seconds, with the belts moving forabout half of this time and the remaining time being spent in the press.During the period the panels are moving the splicing operation takesplace.

FIGURE 4 illustrates the hot plate press. The upper platen 26 is movableand the lower platen 23 is stationary. The upper platen and also thelower platen, if desired, may be heated in any conventional manner. Thebelts 12 run over blocks or the like 30 which are upwardly biased bysprings 32 to the position of FIGURE 4. When the upper platen 26 comesdown, and the panel to be pressed is in position, the belts will bedepressed so that they will be level with the upper surface of the lowerplaten 28 during bonding. The time in the press will depend upon thethickness of the veneer and the type of adhesive. A 5 to lO-secondperiod in the press has been found to be satisfactory.

After a sufiicient time in the press, the belts 12 will move the panelout of the press to the next station indicated at 3 The direction ofmovement of the panel will now be changed, to that indicated by thearrow 36, and after the next rest period during which a panel is bondedin the press 24 and veneer strips are laid on another panel, the beltswill move the panel through a bending station indicated at 38. Heatplates positioned at different angles relative to the panel surface orheated twisted plates, as at 39, along the edges of the panel, will beused to bend the veneer lips which extend over the panel surface downalong the edges of the panel. This is done as the panel is moved. Afterthe bending step the panel will stop at the next station indicated at40, and while the panel is at rest at this point, the edges will bebonded to the panel by means of hot bars or the like 41.

After edge bonding has been completed, the panel will move past a pairof spaced trimming saws 42 which will remove any projecting veneer alongthe edges of the panel. Sanding discs or sanding belts are equallysatisfactory for trimming.

After the edges have been trimmed, the panel again will changedirection, as indicated by arrow 44, and will be moved past saws or thelike 46 which will trim the ends of the panel to the length desired. Theveneer alone may be trimmed, or both the veneer and panel may be cut.

FIGURES 2 and 3 illustrate in detail the operation at the splicing zone.A pair of spaced bars or rods 58 which may be heated in any conventionalmanner, for example steam, electricity, or oil, are positioned above apanel 60 carrying a veneer sheet 62 on its upper adhesive coatedsurface. The bars 58 may be pivoted, as at 64, and may receivedownwardly directed yielding pressure from the spring arrangement 66. Itshould be noted that the lower surface of the bars 58 is upwardlycurved, as at 68, so that at the joint between adjacent spaced veneeredges, the lower edge of the bar is spaced a distance from the panel 60greater than the thickness of the veneer. This is necessary in order toallow the veneers to be moved into edge contact.

A drum 70, which may be rotated in any conventional manner, and is movedat a peripheral speed greater than the speed of the belts 12 and thepanel 60, has a pair of spaced collars each comprising an inner metalring 72 and an Outer ring 74 formed of a cushion material, for examplesponge rubber or the like. An outer layer 76, formed of a thin rubber,is placed on the cushion layer 74 to provide traction.

In operation, the spaced collars on the drum 70 will contact a veneersheet on its upper surface and will slide the veneer sheet toward thenext adjacent sheet. The pressure applied by the spaced collars in adirection parallel with the panel 60 will be greater than the resistanceof the dry adhesive to this sliding movement. As the drum rotates at aperipheral speed greater than the speed of the panel, the veneer sheetindicated at 78 in FIGURE 2 will slide into edge contact with the veneersheet 62. Once these two sheets are in edge contact, they will bemaintained in edge contact by the continuing pressure applied by therotating drum 70. As the resistance to further movement of the veneer'78 is greater than the horizontal component of the pressure applied bythe rotating collars, the collars will slip over the upper surface ofthe veneer thus maintaining edge contact. In a modified arrangement, afriction clutch may be provided so that slippage takes place in theclutch after the veneers are in edge contact.

As stated above, the lower surface 68 of the bars 58 is curved so thatthe veneers may be slid together. In addition this curved surface willtend to gradually flatten buckled veneers so that they may be thenbonded along spaced lines to the panel or substrate 60. It is importantto note that spot bonding is done while the panel is in motion andtherefore the hot bars are never in contact with the veneer more than afew seconds. There is therefore no scorching of the veneer surface. Thebonding will take place along spaced lines which run across the grain ofthe veneer sheets.

The use, operation and function of the invention are as follows:

The present invention is directed to a high speed process suitable forbonding veneer strips to a panel. The veneer should be dry. A thicknessof about inch to & inch is satisfactory, although this is not alimitation. Each of the panels to he veneered is first covered with anadhesive and the adhesive is either force dried or allowed to air dry.The panels are then stacked and removed one at a time by a workmanduring the period when the belts are at rest. One of the panels isplaced across the belts and a group of veneer sheets are placed on topof the adhesive coated surface. The sheet along one edge of the panel isflattened and bonded along parallel lines or otherwise temporarilybonded to the panel. The panel then passes through a splicing zone inwhich each sheet of veneer is automatically and successively flattenedand moved into edge contact with the adjacent sheet of veneer and thentemporarily bonded to the underlying panel. The first sheet is held tothe panel by such temporary bonding to provide an edge against which asucceeding veneer sheet is shoved and held While it likewise istemporary bonded along parallel lines. This splicing step takes placewhile the panel is moving. After bonding the veneer to the surface andedges permanently, the edges are trimmed, in both directions, tocomplete the formation of the veneered panel.

Of particular importance in the invention is the fact that the splicingstep takes place while the panel is moving. Heretofore it was necessaryto perform the splicing step either by hand, or by machine, but in anyevent, While the panel was stationary. The present invention greatlyincreases the speed of the entire panel veneering process. By using thinveneers, dry adhesive, and a very short time in the hot press,commercially flat panels may be produced even though the veneer isapplied to only one side.

Whereas the preferred form of the invention has been shown and describedherein, it should be realized that there are many modifications,substitutions and alterations thereto, within the scope of the followingclaims.

I claim:

ll. A method for applying veneer to one surface of a ligno-cellulosicpanel by a high speed process, which includes the steps of,

applying a liquid adhesive to one surface of a panel having aligno-cellulosic surface,

drying the adhesive,

placing the panel on means adapted to convey the panel to a splicingstation,

while the panel is in motion, temporarily bonding a first veneer sheetto the panel at a bonding station by applying pressure and heat alongspaced parallel lines whose position is fixed,

placing a second veneer sheet on the panel in spaced relationship to thefirst veneer so that there is a gap between the adjoining edges,

and while the panel is in motion, closing the gap between thetemporarily bonded first veneer sheet and a second veneer sheet at thesplicing station, said gap being closed by sliding said second veneersheet on the adhesive until it comes into contact with the edge of thefirst veneer sheet which has been temporarily bonded to the panel,

maintaining edge contact While the panel moves and While the secondveneer sheet is temporarily bonded to the panel along spaced parallellines whose position is fixed,

moving the panel to a permanent bonding station, and

permanently bonding the temporarily bonded veneer sheets over the entirepanel by heated pressing means.

2. A method for applying veneer to one side of a lignocellulosic panelwhich includes the steps of,

applying liquid adhesive to one surface of a panel having aligno-cellulosic surface,

drying the adhesive,

placing the panel on means adapted to convey the panel to a splicingstation,

temporarily bonding a first sheet of veneer to the panel,

placing a second veneer sheet on the dry adhesive,

positioning said sheets in spaced relationship so that there is a gapbetween the adjoining edges of said successive sheets, and while thepanel is in motion, closing the gap between the temporarily bonded firstveneer sheet and a second veneer sheet at a splicing station by slidingsaid second veneer sheet on the adhesive until it comes into contactwith the edge of the veneer sheet which is temporarily bonded to thepanel,

maintaining edge contact while the panel moves and while pressure andheat are applied along parallel lines whose position is fixed, therebytemporarily bonding the second sheet to the panel,

moving the panel to a permanent bonding station, and

permanently bonding the temporarily bonded veneer sheets over the entirepanel by heated pressing means.

3. The process of claim 2 further characterized in that following thestep of obtaining edge contact, said edge contact is maintained by meanswhich slips over the surface of the veneer.

References Cited by the Examiner UNITED STATES PATENTS 1,875,056 8/1932Loetscher 156-291 2,572,772 10/1951 Skoog 156-296 2,587,985 3/1952Elmendorf 156-71 3,031,356 4/1962 Bousquet et al 156-202 3,133,8505/1964 Alenius 156-558 EARL M. BERGERT, Primary Examiner.

1. A METHOD FOR APPLYING VENEER TO ONE SURFACE OF A LIGNO-CELLULOSICPANEL BY A HIGH SPEED PROCESS, WHICH INCLUDES THE STEPS OF, APPLYING ALIQUID ADHESIVE TO ONE SURFACE OF A PANEL HAVING LIGNO-CELLULOSICSURFACE, DRYING THE ADHESIVE, PLACING THE PANEL ON MEANS ADAPTED TOCONVEY THE PANEL TO A SPLICING STATION, WHILE THE PANEL IS IN MOTION,TEMPORARILY BONDING A FIRST VENEER SHEET TO THE PANEL AT A BONDINGSTATION BY APPLYING PRESSURE AND HEAT ALONG SPACED PARALLEL LINES WHOSEPOSITION IS FIXED, PLACING A SECOND VENEER SHEET ON THE PANEL IN SPACEDRELATIONSHIP TO THE FIRST VENEER SO THAT THERE IS A GAP BETWEEN THEADJOINING EDGES,S, AND WHILE THE PANEL IS IN MOTION, CLOSING THE GAPBETWEEN THE TEMPORARILY BONDED FIRST VENEER SHEET AND A SECOND VENEERSHEET AT THE SPLICING STATION, SAID GAP BEING CLOSED BY SLIDING SAIDSECOND VENEER SHEET ON THE ADHESIVE UNTIL IT COMES INTO CONTACT WITH THEEDGE OF THE FIRST VENEER SHEET WHICH HAS BEEN TEMPORARILY BONDED TO THEPANEL, MAINTAINING EDGE CONTACT WHILE THE PANEL MOVES AND WHILE THESECOND VENEER SHEET IS TEMPORARILY BONDED TO THE PANEL ALONG SPACEDPARALLEL LINES WHOS POSITION IS FIXED, MOVING THE PANEL TO A PERMANENTBONDING STATION, AND PERMANENTLY BONDING THE TEMPORARILY BONDED VENEERSHEETS OVER THE ENTIRE PANEL BY HEATED PRESSING MEANS.